Wear-resistant, superabrasive materials are traditionally utilized for a variety of mechanical applications. For example, polycrystalline diamond (“PCD”) materials are often used in drilling tools (e.g., cutting elements, gage trimmers, etc.), machining equipment, bearing apparatuses, wire-drawing machinery, and in other mechanical systems.
Superabrasive elements having a superabrasive body or layer (e.g., a PCD table), may be formed and bonded to a substrate to form a compact, such as a polycrystalline diamond compact (“PDC”). Often, superabrasive elements that have a PCD table are fabricated by placing a cemented carbide substrate, such as a cobalt-cemented tungsten carbide substrate, into a container with a volume of diamond particles positioned on a surface of the cemented carbide substrate. The substrate and diamond particle volumes may then be processed under diamond-stable high-pressure high-temperature (“HPHT”) conditions in the presence of a catalyst material, which causes the diamond particles to bond to one another to form a diamond table including a plurality of bonded diamond grains having interstitial regions therebetween. The catalyst material is often a metal-solvent catalyst, such as cobalt, nickel, or iron, which facilitates intergrowth and bonding of the diamond crystals. The catalyst may sweep in from the cemented-carbide substrate, such as cobalt from a cobalt-cemented tungsten carbide substrate, which liquefies and sweeps from a region adjacent to the volume of diamond particles into interstitial regions between the diamond particles during the HPHT process.
The presence of the metal-solvent catalyst and/or other materials in the PCD table may reduce a thermal stability of the PCD table at elevated temperatures. For example, a difference in the coefficients of thermal expansion between the diamond grains and the metal-solvent catalyst is believed to lead to chipping or cracking in the PCD table of a cutting element during drilling or cutting operations. The chipping or cracking in the PCD table may degrade the mechanical properties of the cutting element or lead to failure of the cutting element. Additionally, at high temperatures, diamond grains may undergo a chemical breakdown or back-conversion to graphite catalyzed by the metal-solvent catalyst.
Chemical leaching may be used to dissolve and remove the metal-solvent catalyst from the PCD table. Conventional chemical leaching techniques include soaking the PCD or the entire PDC in highly concentrated and corrosive (e.g., strongly acidic or basic) leaching solutions to dissolve and remove metal-solvent catalysts from PCD.
However, typical soaking times for the leaching process may include days, weeks, or months. Further, the leaching solutions can dissolve any portions of the substrate exposed to the leaching solution. Accordingly, when a PCD must be leached—in order to limit potential damage to the substrate—the PCD can be formed, leached, and then bonded to a substrate, or a masking technique can be used during leaching of a PDC.
Manufacturers and users of superabrasive elements, such as PDCs, continue to seek improved processing techniques.